This invention relates to crystalline polymorphs of 8-chloro-6,11-dihydro-11-(4-piperidylidene)-5H-benzo[5,6]cyclohepta[1,2-b]pyridine (hereinafter xe2x80x9cdescarbonylethoxyloratadinexe2x80x9d) represented by the formula 
pharmaceutical compositions containing such polymorphs, and methods of using such polymorphs to treat allergic reactions in mammals.
U.S. Pat. No. 4,659,716 discloses descarbonylethoxyloratadine which possesses antihistaminic properties with substantially no sedative properties. This U.S. Patent also discloses methods of making descarbonylethoxyloratadine and using it to treat allergic reactions in mammals.
To prepare pharmaceutical compositions containing descarbonylethoxyloratadine for administration to mammals in accordance with exacting health registration requirements of the U.S. and international health registration authorities, e.g. the FDA""s Good Manufacturing Practices(xe2x80x9cGMPxe2x80x9d)requirements, there is a need to produce descarbonylethoxyloratadine in as pure a form as possible, especially a form having constant physical properties.
We have discovered that descarbonylethoxyloratadine can exist in the form of two distinct crystalline polymorphs, each having distinctly different physical properties.
Accordingly, this invention provides crystalline polymorph form 1 descarbonylethoxyloratadine essentially free of polymorph form 2 and characterized by the following x-ray powder diffraction pattern having characteristic peaks expressed in terms of xe2x80x9cdxe2x80x9d spacing and relative intensities(xe2x80x9cRIxe2x80x9d) at approximately:
This invention also provides crystalline polymorph form 1 descarbonylethoxyloratadine essentially free of polymorph form 2 and characterized by the following x-ray powder diffraction pattern essentially free of poymorph form 2 and having characteristic peaks expressed in terms of xe2x80x9cdxe2x80x9d spacings and relative intensities (xe2x80x9cRIxe2x80x9d)(s=strong, m=medium, w=weak, v=very and d=diffuse) at approximately:
This invention further provides crystalline polymorph form 2 descarbonylethoxyloratadine substantially free of poymorph form 1 and characterized by the following x-ray powder diffraction pattern having characteristic peaks expressed in terms of xe2x80x9cdxe2x80x9d spacing and relative intensities(xe2x80x9cRIxe2x80x9d) approximately:
This invention also provides crystalline polymorph form 2 descarbonylethoxyloratadine substantially free of poymorph form 1 and characterized by the following x-ray powder diffraction having characteristic peaks expressed in terms of xe2x80x9cdxe2x80x9d spacing and relative intensities (xe2x80x9cRIxe2x80x9d) s=strong, m=medium, w=weak, v=very and d=diffuse) at approximately: